In water, it breaks down into magnesium and sulfate. The theory is that when you soak in an Epsom salt bath, these get into your body through your skin. That hasn’t been proven, but just soaking in warm water can help relax muscles and loosen stiff joints.
People use Epsom salt baths as a home treatment for:
Arthritis pain and swelling
Bruises and sprains
Fibromyalgia, a condition that makes your muscles, ligaments, and tendons hurt, and causes tender points throughout your body
Ingrown toenails
Insomnia
Psoriasis, a disease that causes red, itchy, scaly skin
Sore muscles after working out
Soreness from diarrhea during chemotherapy
Sunburn pain and redness
Tired, swollen feet
While there are plenty of folk remedy claims, there aren’t a lot of studies to back them up. Taking this type of bath probably won’t hurt you, but if you have health concerns, check with your doctor first.